FDA: Zika tests may produce false positives

Health care providers should “inform their patients that presumptive positive results
need to be confirmed, so that pregnant women are not making health care decisions
based on incomplete information,” the Food and Drug Administration (FDA) said in a
safety alert.

Zika virus is spread by Aedes mosquitoes.

The warning stems from Laboratory Corporation of America reporting more false positives
than expected from the ZIKV Detect IgM Capture ELISA manufactured by InBios International
Inc., according to the FDA. Less than half of the presumptive positive results were
confirmed by the Centers for Disease Control and Prevention (CDC). The FDA has not
determined the cause of the false positives.

As it investigates, the FDA is reminding health care providers the IgM test results
are presumptive and require confirmatory testing by the CDC or other qualified laboratories,
which may take as long as a month. Physicians should consider clinical observations,
patient history, epidemiological information and other test results when diagnosing
a pregnant woman. They can notify a laboratory of a woman’s pregnancy to expedite
confirmatory testing.

There have been 4,866 cases of Zika virus in U.S. states and Washington, D.C., including
1,292 pregnant women, according to the CDC. Most have been travel-associated as only
Florida and Texas have reported local transmission of the virus. In U.S. territories,
there have been 35,415 cases of Zika, including 2,842 pregnant women.

The Academy recently launched a new webpage that features a compilation of the CDC’s
key guidance on Zika characteristics, testing, evaluation, treatment and follow-up
at http://bit.ly/2j24yF2.